Process of making mixed esters of cellulose



atente' Get. 3:, 133 v Ne. Drawing. Applicants. .nuy" as, 1931 a .Serialn 553,683

18 meal. "(or sea-1th This invention relates to the, makmg ofvariousmulti-acyl'ated cellulose derivatives "by introducing organicacid'radicals into higher fatty acid esters or" cellulosalbothsimple'and mixed) I higher esters of cellulose are susceptible of fur--Which havebeen partially hydrolyzed.

An object of our invention is to provide a process for making themixedesters of cellulose in which the proportions of acyl radicalsmay becontrolled. 1

Another object of our invention uses, some of which uses are not usuallyconsidered as adapted to the employment oi esters of cellulose.

Hitherto the production of the mixedesters or cellulose has been eitherbyesteriiying cellulose with an acylati'ng mixture which contributes aplurality of 'organic acid--radicalsto the ceilu lose or by esterifyingan acetone-soluble cellua lose acetate as? disclosed, for example, in U;S. Patent No. 1,698,043 to Clarke and Malm. The former method does-notadmit of asaccurate and precise control as may sometimes be desirable incommercial manufacture. The latterprocessis not 'as Well suited as theherein described process for the production of certain mixed esters ofcellulose which do not contain the acetyl group cation to formmulti-acylated estersot cellulose.

We have found that by reason'o'i the control of the content of acylgroupspossible in the hydrolysis of the higher esters of cellulosegprecise regulation of the type of mixed-esters of cellulose resultingfrom our process is facilitated. Some of the esters which, whenpartially hydrolyzed are r suitable forfurther esterification arecellulose propionate. cellulosebutyrate, cellulose acetate propionateand cellulose acetate-butyrataas Well as esters containing higher acylradicals such as cellulose laurate, cellulose stearate, cellulose'acetate-laurate and cellulose acetate ste'arate. The hydrolysis of themixed esters of cellulose may be carried out by the inetliodof Malrn andFletcher application, serial No. 551,546, which dis closes that thehydrolysis may be carried out in an aqueous organicaciclsolution forexample, at.

V to providea' process of making cellulose esters having dis'tinc tiveproperties which adapt them for particular We have found that thepartiallyhydro about 100 F. The simple esters may be hydro lyzed by alike method or by any method.dis-' closed in-the prior art. 1 1

-We have'found; that the partially hydrolyzed ther esterification by (-1fattyacid anhydrides, (2) fatty acids together with an impeller or (3)fatty acid chlorides. Theesterification by means of a fattyacidanhydride may be carried out eitheir in a solvent'reaction mixture or byfibrous acylation' in a liquid such as toluene which is a non-solventboth for the hydrolyzed ester and for the final product. Varioussuitable liquids suchas, for example, monochloracetic acid, alkoxyaceticacid, ethylene chloride, etc. or, in some cases, the acidcorrespondingto the anhydride employed or even a" diilerent organic acidmay be used as the'solvent whenesterifying ina sol: vent reactionmixture.

v The following examples areillustrative ofthe application of ourinvention to the production, or mixed esters of cellulose; i Y

Example I 160 lbs. of cellulose propionate which hasbeen hydrolyzed to apropionyl content of about/5%, is placed in a reaction bath containing480 lbs. o1": stearic acid, 400 lbs. of chloracetic anhydride, 8e0'1bs.of chloracetic acid and a small amount of a catalyst, such as magnesiumperchlorate.

The mass is heated to about C. foryabout 6 hours. The ester obtained maythenbe isolated from the reaction mixturezby. precipitat j ing in methylalcohol. 1 Y The. product formed is cellulose propionatef stearatewhichis acetone-soluble andis also soluble in hot mineraloil of mediumviscosity, which solution uponv cooling forms a jell of the con- 2si'stency of heavy grease. W

Example II lbs. of cellulose propionate containing about 45% propionylis placed in a'reaction bath containing 300 lbs. of glacial 'aceticacid,250 lbs."

of acetic anhydride and aismall amountof "sulfuric acid. Themass ismaintained at about 32 C. for several hours. lhe resultingester may;then be precipitated in dilute acetic acid accordingto themethoddisclosed in Malm application No. 553.6%7. Y

The resulting product is cellulose-acetate-propionate which is soluble:in acetone, ethylene chloride and methyl acetate. 1

Ii desired, the temperature maybe maintained at,l866qC. in which case,the time and the amounts of acid and anhydridemay be reduced. In suchcase, a buffer such as sodium acetate, or some other alkali metal saltmay be added, if desired, to eliminate any danger of degradation.

Example III l00lbs. of cellulose butyrate having about 50% butyrylcontent is placed in a reaction mixture containing 200 lbs. of stearicanhydride, 800 lbs. of ethoxy-acetic acid and a small amount ofmagnesium perchlorate. about 65 C. for about 10 hours at the end ofwhich time the resulting ester may be separated from its reactionmixture by pouring the latter with agitation into methyl alcohol. Thecellulose butyrate-stearate formed is: soluble in various hydrocarbonssuch as mineral oil, ligroin, etc.

as well as in vegetable oils such as castor oil.

Example IV Example V 100 lbs of cellulose butyrate having about a 50%butyryl content W rich has been subjected to 100 hours hydrolysis isplaced in a reaction mixture containing approximately 1500 lbs; of

toluene, 150 lbs. of propionic anhydride and 40 lbs. of pyridine. Themixture is refluxed for 15-30 hours. The cellulose ester obtained isfiltered off and washed. A cellulose propionatebutyrate is obtained.

7 Example VI 100 lbs.'of cellulose acetate-proprionate, having about a30% acetyl and 12% popionyl content is placed in about 1500 lbs. oftoluene.

The moisture present is distilled off and a mixture of about 500 lbs; ofstearic anhydride, 30 lbs. of p-toluenesulfo-chloride and 1500 lbs. ofligroin (B. P. 90-120 C.) is added. The mixture is refluxed for 15-30hours, depending upon the speed of the reaction after which thecellulose ester mayj be filteredoff .and washed with hot water ifdesired. A cellulose acetate-propionate-stearate is obtained.

Example VII 100 lbs. of cellulose butyrate, having about a butyrylcontent is placed in 300 lbs. of pyridine, and 400 lbs. of laurylchloride in 400 lbs. oftoluene is added. The mass is heated for 3-5hours at about 50 C. or until complete acylation occurs. The cellulosebutyrate-laurate obtained is separated from the reaction mass by pouringthe latter with agitation into methyl alcohol. The ester is soluble inacetone, ethyl acetate, benzene and chloroform.

Example VIII 100 lbs. of cellulose butyrate having about a 50% butyrylcontent is placed in a reaction mix- Themass is kept at ture containingabout 200 lbs. of stearic anhydride, 800 lbs. of ethylene chloride and asmall amount of magnesium perchlorate. The mass is kept at about C. forabout 10 hours at the end of which time the resulting ester may beseparated from its reaction mixture by pouring the latter with agitationinto methyl alcohol. The cellulose butyrate-stearate formed is solublein various hydrocarbons such as mineral oil, ligroin etc. as well as invegetable oils such as castor oil.

As pointed out before, the esters of cellulose containing high radicals,such as lauryl, stearyl,

palmityl, etc., when partially hydrolyzed, may be employed as thestarting material for adding additional acyl groups according to themethod disclosed by the above examples. However, it is preferred tostart with the propionate or butyrate containing esters and substituteother groups therein.

If desired, a'series of acylations, according to our process, may beemployed to prepare esters having several different acyl radicalsattached to the cellulose. For example, a hydrolyzed cellulosepropionate may be esterified according to our process by which abutyrate group added. This cellulose propionate-butyrate may then behydrolyzed and the resulting hydrolized cellulose propionate-butyratemay then be esterified with the addition of a lauryl group. Thus, acellulose propionate-butyrate-laurate may be formed. Still furtherhydrolysis and esterifiedtion is, of course, possible if the addition ofstill further groups is desired.

If desired, more than one group may be added to the hydrolyzed esterupon esterification. For example, hydrolyzed cellulose propionate may beesterified in a bath containing acetic anhydride and lauric acid or itmay, for example, be esterified in a bath containing an impeller such asethoxyacetic anhydride and a plurality of organic acids.

The catalysts which will promote acylation reactions are well known andneed not be enumerated here. It is, of course, within the judgmentol theskilled artisan'to determine which of these acylation catalysts is mostsuitable for the particular esterification which he desires to carryout. The employment of any of the known catalysts for acylation in ourprocess comes within the contemplation of our invention. The varioussolvents or non-solvents which may be employed in the esterificationaccording to our process are also a matter of choice and the selectionof a particularly well known solvent for carrying out the esterificationof the hydrolyzed esters according to our process is within the scope ofour invention.

The esters which are produced by our process may be employed for manyand various uses, such as the forming of sheets or films, filaments forartificial silk, lacquers, lubricants, artificial leather, materials formoulding, waterproof coating or any other capacity in which celluloseesters have previously been employed. Many of the esters made accordingto our process have qualities which give them exceptional adaptabilityin this art, for example, some of these esters give films and filamentswithout employing plasticizers. triphenyl or tricresyl-phosphate, may beincorporated with the esters produced by our process when formingcolloidized products therefrom.

Our esters may also be mixed with other cellulose esters, such ascellulose acetate or cellulose However, compatible plasticizers such ascellulose which comprises treating a hydrolyzed nitrate and/or withother plastic materials such as gums, resins, waxes, heavymetal soaps,etc.

7 lulose with an esterifying bath containing They may also be employedfor laminating or reinforcing glass, cellulose derivatives or other theyare in sheet'or materials, especially when layer form. I

Other modifications of our process and other uses forthe esters soproduced which will occur to those skilled in the art also come withinthe contemplation of our invention.

' It is to be understood that the term higher organic is employed hereinto designate either radicals above acetyl in the number of carbon atomsor esters which contain such radicals.

What we claim as our invention is:

1. The process of producing a mixed ester of cellulose which comprisesesteriiying a partially hydrolyzed acyl ester of cellulose containing ahigher aliphatic acid radical and 1-4 hydroxyl groups-to every 24carbonatom unit of cellulose.

2. The process of producing a mixedester of cellulose which comprisesesterifying a hydrolyzed acyl ester of cellulose containing the radic-alof a fatty acid higher than acetic and l-4 hydroxyl groups to every 24carbon atom unit or cellulose.

3. The process of producingfa mixed ester of cellulose which comprisesesterifying a hydrolyzed acyl ester of cellulose containing an aliphaticacid radicalof 3-4 carbon atoms and l-j4 hydroxyl groups to every 24carbon atom unit of cellulose. 4. The process of producing a mixed esteiof cellulose which comprises treating a hydrolyzed acyl ester ofcellulose containing a higheraliphatic radical and 1-4 hydroxyl groupsto every 24 carbon atom unit of cellulose with an esterify-- ing bathcontaining an aliphatic acid anhydride. 5. The process of producing amixed-ester of cellulose which comprises treatinga' hydrolyzed acylester of cellulose containing a higher aliphatic radical and 1-4hydroxylgroups to every 24 carbon atom unit of cellulose with anesterliying bath containing analiphatic acid anhy- 'drideand a catalyst.I

6. The process of producing a mixed ester of cellulose which comprisestreating a. hydrolyzed acyl ester of cellulose containing an aliphaticacid radical of 3-4 carbon atoms and 1-4 'hydroxyl groups to every 24carbon atom unit of cellulose with an esterifying bath containing analiphatic acid anhydride. Y

7. The process of producing a mixed ester of cellulose which comprisestreating a hydrolyzed V acyl ester of cellulose containing an aliphaticacid radical of 3-4 carbon atoms and 1-4 hydroxyl groups to every 24carbon atom unit of celan aliphatic acid anhydride and a catalyst. v

8. The process of producing a mixed .ester of cellulose which comprisesesterfying a hydrolyzed acyl ester of cellulose selected from the groupconsisting of'cellulose propionate, cellulose losceacetatebutyrate and1-4 hydroxyl groups to every 24 oarbon atom unit of cellulose.

9. The process of producing a mixed ester of cellulose which comprisestreating ahydrolyzed acyl ester oicellulose selected from the groupconsisting of cellulose propionate, cellulose bu tyrate, celluloseacetate-propionate, and cellulose acetatebutyrate and 1-4 hydroxylgroups to every 24 carbon atom unit of cellulose with an esterifyingbathcontaining an aliphatic acid anhydride.

10. The process of producing a mixed ester of acyl ester of cellulosecontaining a higher aliphatic radical and l-4 hydroxyl groups to every24 carbon atom unit of cellulose with a bath containing an .esterifyingagentselected from the group consisting of a fatty acid anhydride, afat-- ty acid and a fatty acid chloride. 4 I

1.1. The process of producingja mixed ester ofcellulose whichcomprisestreating a hydro: lyzed acyl ester of cellulose containing a higheraliphatic radical and 1-4 hydroxyl groups to every 24 carbon atom unitof cellulose with an esterifying bath containing a fatty acidanhydrideand an organioliquid which is at least a solvent for the anhydride. V

12. The process of producing a mixed ester of cellulose which comprisestreating a hydrolyzed acyl ester of cellulose containingfa higheraliphatic radical and 1-4 hydroxyl groups to every 24 carbon atom unitof cellulose with an esterifying bath containing a fatty aoidand anorganic liquid which is at least a solvent for the acid. 1

13. The process of producing a mixed ester of cellulose which comprisestreating a hydrolyzed acyl ester of cellulose containing a higheraliphatic radical and 1-4 hydroxyl groups to every 24 carbon atom unitof cellulose with an esterifying bath containing a fatty acid chlorideand an organic liquid which is at least a solvent for the chloride.

14. Theproc ess of producing a mixed esterof cellulose which comprisestreating a hydrolyzed acyl ester of cellulose containinga higheraliphatic radical and 1-4 hydroxyl groups to every 24 carbon atom unitof cellulose with an esterifying bath containing a fatty acid anhydride,a catalyst and an organic liquid which is at least a solventfor theanhydride.

15. The process of producing a mixed ester of I cellulose whichcomprises treating a hydrolyzed acyl ester of cellulosecontaining ahigher aliphatic radical and 1-4 hydroxyl groups to every.

24 carbon atom unit. of cellulose withan esterileast a solvent for thefying bath, containing a fatty acid chloride, a.

catalyst and an organic liquid which is at least a.

solvent for the chloride.

17. The process of producing a mixed esterof cellulose which comprisestreating a hydrolyzed acyl ester of cellulose containing a higheraliphatic acid radical and 1-4 hydroxyl groupsto every 24 carbon atomunit of cellulose-With an esterifying bath comprising a fatty acid, animv peller forthe esterification anda catalyst.butyratecelluloseacetate-propionate and cellu- 18. Theprocess ofproducing a mixed ester of cellulose Whichcomprises treating ahydrolyzed acyl ester of cellulose containing a higher fatty acidradical and 1-4 hydroxyl groups to every 24 carbon atom unit ofcellulose with an esterifying bath comprising a fatty acid and an im-

